What are some reputable agencies in Bangkok for obtaining a Covid visa extension?

I'm looking for recommendations for a reputable agent in Bangkok...I know, I know :-)

I only need a Covid extension done, nothing tricky or sneaky.

I came to Thailand for medical treatment, which has left me with lowered immunity.

I'm only trying to avoid going to a crowded place during a Covid outbreak....so I'm willing to pay an agent to go in my place, if that's possible.

I'd love to get recommendations for visa companies that have been around a long time and who you may have used yourself.

Thank you!